Kingdom Hearts Zero: Light Unto Darkness
by The Everlasting
Summary: All darkness has its roots in light, no matter how black it is. Over fifty years before Birth by Sleep, Xehanort was merely an apprentice alongside Eraqus and Yen Sid. However, when a force invades the Realm of Light, the three are sent to stop it and defeat a mysterious armored man. When embarking on his journey, Xehanort's destiny, and his beliefs, will change forever.
1. Prologue

On a world of crashing waves, sunny days and a cheerful atmosphere, a young man stands at the shore, with silver hair, golden eyes, dark skin, and an outfit primarily consisting of black and grey. The man's name was simply Xehanort.

"This world is just too small," Xehanort said, lamenting how limited everything in the world of Destiny Islands was. Despite it being all he's ever known, Xehanort had always dreamed of more, of places beyond his world to explore, even though he had no means of reaching them, should they even exist.

 _If I were to leave here, probably forever, would anyone miss me?_ Xehanort wondered internally. _After all, I have no family, very few friends, and no accomplishments in my life or goals for the future. It would be so easy for me to just disappear._

Suddenly, a cluster of dark clouds rolled in out of the blue, obscuring the bright sun and casting Xehanort in shadow. A few seconds later, as if the universe had listened to his thoughts, a strange black and white portal emerged a mere few feet away from him.

 _Well, aren't you an interesting object?_ Xehanort thought, as he stepped closer to the portal. _I wonder if you'll lead me to where I desire to go._ Tentatively, Xehanort reached his arm into the portal, feeling it burning hot and freezing cold both at once. In response to his pain, Xehanort attempted to remove his arm, but found that he was slowly getting pulled further in. However, his greatest desire quickly filled his thoughts and he ceased resistance, stepping inside as darkness overtook him.

—

With every muscle in his body aching, Xehanort finally managed to open his eyes. He expected it to have all been a weird dream with his aches being the result of some misshapen sleeping position, but he quickly realized that he was not in his room.

"Where… am I?" He wondered aloud, wandering forward as he took in his surroundings.

Looking around, Xehanort saw a magnificent white and golden castle in front of him, with a series of steps leading to it, and large mountains and valleys strewn about the landscape. It appeared to be midday, judging by the position of the sun, but he had no way of accurately determining it.

"So Yen Sid, looks like it's time for lunch break, huh?" A masculine, yet rather soft, voice said from behind the lost islander, causing him to turn his head in confusion.

"That it is, Eraqus," another voice, this one deeper, replied.

Internally panicking over who the two may be, Xehanort simply froze, waiting to see the two inhabitants of the world he miraculously ended up in.

After a few seconds, two boys of similar age to Xehanort himself stepped up to the platform he was currently on. One of them had black hair in a small ponytail, with a tan cloak, golden boots and a sort of armor covering his torso, colored dark blue, sea green and silver, with an ornate insignia engraved in the chest. The other boy was wearing a deep blue robe with turquoise trim and a wizard's hat with yellow stars and a crescent moon printed on it.

"I wish the Master weren't so insistent on our training. Honestly, with training like thi…" The first boy paused upon seeing Xehanort, stopping in his tracks. The other one simply stared intently at Xehanort, viewing him as though he were a cornered animal that had been caged for study.

"Hey… you're not supposed to be here," the first boy said as he approached Xehanort, "we won't hurt you, don't worry."

The silver-haired youth was too panicked by his predicament to listen to the other boy. Sweat rolled down his neck as his eyes flitted around with worry and trepidation.

" _Where am I? How did I get here? Who are these people?!_ " he asked, but his fear had overtaken his senses, and no words left his mouth.

Xehanort began stepping backward to create some distance between the pair and himself, but soon tripped out of fright, landing on the ground with a solid thud.

"Stay back," he commanded, keeping a flat tone of voice as to not sound hostile.

"I said we wouldn't hurt you, young man. Now just stand up and we'll try to help," he said, ignoring Xehanort's words and getting closer to the newcomer.

"I said stay back!" Xehanort shouted, standing up. Suddenly, power surged through him as some sort of energy manifested in his right hand. The energy coalesced into a strange weapon in moments, prompting the silver-haired youth to attack the boy in front of him with it, but the boy had generated a similar weapon in the same instant and blocked the blow.

"Whoa, take it easy, I never figured you could wield a Keyblade," he said casually, not paying heed to the weapon a few inches from his skull.

"Key… blade?" Xehanort asked, confused. Looking more closely at the weapon in his hand, the end of the blade seemed to resemble a clock striking one, with several dark blue and curved blades protruding from the end, and various dark blue and cyan gears forming the blade itself, as well as the guard and hilt. Attached at the end was a chain, the end holding a crown.

"Oh, so this is your first time summoning it, huh?" The black-haired boy dissolved his Keyblade and stepped to the side, throwing Xehanort off balance and allowing him to fall to the ground once more. "I should show you to the Master. The name's Eraqus, and that's Yen Sid," he motioned to the other boy as he helped the golden-eyed youth up.

"Xehanort. I have no idea just how I got here, but maybe this Master of yours knows something," Xehanort explained, still holding his Keyblade. Eraqus lead him up the steps to the castle, with Yen Sid following close behind.

"So, just to shed some light on my current situation, just where _am_ I?" Xehanort asked when they reached the main door.

"This world is called the Land of Departure. It's where the Keyblade Masters of old had their training. Been like that since this world's existed," Eraqus explained.

Xehanort's gaze widened as he listened to Eraqus' words, "Wait… did you say 'world'?"

"That I did," the black-haired youth replied, "Is there something wrong with that?"

Any trace of fear had been replaced by the excitement coursing through the newcomer's veins, "So other worlds _do_ exist. I knew they weren't just fairy tales. Say, how many worlds-"

"Perhaps you can hold the questions for now. Master Inex should be able to tell you more," Yen Sid interrupted, gesturing to Eraqus to open the door. Eraqus did so, bringing the three of them to a large, ornate room with three, rather out of place, simple wooden thrones at the end of the hall. Sitting in the center throne was a man much older than the two next to him, with light brown hair, a very deep blue coat with yellow trim, underneath holding a white shirt and brown pants, boots holding similar color to his coat and a small pair of reading glasses, through which he was reading a fairly sizeable tome that rested in his lap.

"Master Inex! We've found another Keybearer!" Eraqus shouted from the other side of the hall. The three boys approached the Keyblade Master, who looked up from his book to inspect the new recruit, raising an eyebrow but cracking a small smile.

"Well, hello, young man. My name is Master Inex, and I believe you've already met my two apprentices, Eraqus and Yen Sid. Tell me, what is your name and how did you happen upon our world, much less wield the weapon of legend?" He asked, closing the book he was reading, a soft smile crossing his features.

"It's Xehanort. I'm from a world called Destiny Islands, but earlier today, I think, some sort of portal brought me here, your two apprentices greeting me shortly after I arrived. In panic induced self-defense, I happened to summon this 'Keyblade', and in response, they brought me before you," Xehanort explained, presenting his Keyblade to the Master.

Inex moved his spectacles down, inspecting the Keyblade intently. "Well, like most Keybearers, it seems your heart sensed your feeling of danger and, with its strength, manifested your Keyblade as a means of defending yourself. I don't fully understand it myself, but it's the best assumption I can manage," Inex said, leaning back in his throne.

"What do you suggest we do, Master Inex?" Yen Sid asked, wondering about the future of the boy they had just met.

"Well, since we do have spare bedrooms here, and you two could really use another partner. Xehanort, how would you like to become my apprentice?" Inex proposed, resting the book at his side and standing up.

The moment Inex finished his sentence, Xehanort began thinking intently. True, this _was_ what he wanted, to explore other worlds and see what they had to offer, and as he noted earlier that day, no one would really miss him back at his home world. However, these were three men he knew nothing about, and they could very well be lying to him, not to mention the dangers that could exist in worlds other than his own. After a solid minute of thought, Xehanort finally responded.

"Yes, Master Inex, I would be glad to become your apprentice and learn the ways of the Keyblade."

"Very well. Eraqus, Yen Sid, please escort your new fellow apprentice to his quarters. They're right next to yours."

Eraqus and Yen Sid nodded, and led Xehanort to a hallway to the left.

" _This is where my new life begins, huh?"_ Xehanort pondered, " _Well, let's hope it's better than my old one."_


	2. Just an Ordinary Day

Xehanort's eyelids peeled open as the sun rose over the horizon, the sun's rays rousing him from his peaceful sleep. The three years away from his homeworld hadn't done much to the youth's appearance, but his hair was cut shorter and it became more disheveled regardless of how much he combed it, several locks draping in front of his face.

While he was getting dressed for the day's training, Xehanort briefly overviewed his days in the Land of Departure. According to Master Inex, Xehanort was something of a prodigy, learning more in a week than most apprentices learned in a month; though he still only had a basic grasp of magic, despite Yen Sid's help in the matter.

Putting on his dark grey boots, tightening his silvery gauntlets and buttoning his black cloak, Xehanort strode out of his room smiling, walking down to the kitchen to meet with Eraqus, and grabbed an apple from a nearby basket.

"You're up early. Again," Eraqus said, chuckling under his breath.

"Hey, I want as much time as I can to do what I love," Xehanort replied, taking a bite out of the fruit in his hand and sitting at one of the granite table's chairs.

"You mean explore other worlds or train? Because you seem to do one more than the other," the black-haired apprentice asked, sitting across from his fellow pupil.

"What? When you take a guy who's lived in one place his whole life and then give him a universe to explore, what do you think will happen?" The golden-eyed youth retorted.

"You make a fair point, but remember what happened the last time you ditched training to see other worlds?" Eraqus said, reminiscing about an event that occurred one month after the boy across from him began his training.

"Oh, don't remind me," Xehanort chuckled, remembering the day just as well.

—

 _With the sunset dying the sky orange, Xehanort flew down to the Land of Departure, dismissing his Keyblade Armor and reverting his wing-like Keyblade Glider back to its default form once he reached the ground. For the last twelve hours, he had been visiting a lovely world known as Radiant Garden instead of training with his fellow apprentices. While the silver-haired youth would normally be apprehensive about simply leaving without noting where he departed to, the thought of visiting new worlds was too tantalizing for his mind to bear. As such, he had left in early morning, hoping vainly that his fellow Keybearers wouldn't notice his absence. The fact that the world had proved particularly interesting hadn't helped matters, but it couldn't be helped._

 _Xehanort silently approached the steps of his new home with cat-like tread, taking special care to avoid making any sound to avoid attracting Eraqus', Yen Sid', or worst of all, Inex's attention. He was told that missing training was a very undesirable action, and that Master Inex loathed the thought of seeing his apprentices slack off. Entering the doors of the Land of Departure's castle, the golden-eyed apprentice treaded carefully to the nearby staircase, trying to enter his room without the other residents knowing._

" _It would be most appreciated if my apprentices did not leave this world without even notifying me of where they went." The voice completely halted Xehanort in his tracks. Looking to his right, he saw his Master sitting on the throne, a slight frown crossing his features._

" _M-Master Inex… I was… I was… gathering information from other worlds. Yeah, to familiarize myself with places besides here," Xehanort said, laughing nervously as he approached Inex, standing a few feet from the throne._

 _Inex sighed, "Now, Xehanort, I am very disappointed in you. While we are all curious, as is human nature, acting upon it can lead to truly disastrous consequences. You are still grasping the basics of Keyblade training; nor have you have you learned any form of magic. If you were to be attacked out there, you would have few options to defend yourself with, which would likely lead to significant injury, or worse, death._

 _Rising from his throne, Inex continued. "Worse still, you did not inform Eraqus, Yen Sid, or myself of where you had gone, or even that you left to begin with. If anything were to happen to you, we would have no idea where to find you, which would have certainly sealed whatever horrible fate could befall you."_

 _After he finished, Xehanort looked downward, afraid to look his master in the eyes. His Master, however, let out a sigh and pushed Xehanort's chin up with his finger._

" _However, my apprentice, I am not angry. I acknowledge that this is a byproduct of your isolated life prior to your arrival here, and you simply want to explore worlds not your own. Believe me, you will be able to in due time, but with your lack of experience in self-defense, exploring now would be foolish, to say the least. In a few years, you'll be ready, but right now you must focus on your training."_

" _I understand, Master Inex. I shall try and focus more on my training in these coming days," Xehanort said, nodding._

" _Very well. Now, off to bed, you'll need your rest for tomorrow's training," the elder man replied, leaving to rest in his own quarters, as Xehanort traveled to his own._

—

"So, Yen Sid should be waiting for us in the courtyard, right?" Xehanort asked, taking the last bite of his apple, "After all, we still have training to do."

"He would be, yes. If I recall, we're supposed to be testing our skills against each other, to see how we fare against other Keyblade wielders, you know?" the black-haired apprentice replied, the two of them standing up and making their way outside of the castle.

"Yes, but what's the purpose? Given their rarity, I doubt we'd meet many new Keyblade wielders in our travels, much less ones that are not only hostile but can wield their weapons well enough to threaten us," the golden-eyed youth inquired.

"Well, you never know, now do you?" Eraqus retorted.

Xehanort gave a half-hearted shrug as he and Eraqus made their way to the courtyard, where Yen Sid patiently waited.

"Ah, there you both are. Now, this shall be a simple sparring session. The two of you will test your skills against each other, to see how you fare against fellow wielders of the Keyblade. There is no punishment for losing, so don't be ashamed if you are outclassed," the apprentice explained as Xehanort and Eraqus stood at opposite ends of the field that would be the location for their battle. The duo then drew their Keyblades and entered their fighting stances, Eraqus wielding his Keyblade in two hands and Xehanort wielding his in one, holding it even with his own head.

"Your move," Eraqus taunted. Without a word, Xehanort rushed forward with incredible speed and swung at Eraqus' midsection, but the opposing Keyblade managed to block the blow mere inches before it would have collided with his body, sparks generating from the clash. In the very next instant, Eraqus parried the blow and sent the other apprentice slightly backwards, before swinging his own Keyblade at Xehanort's shoulder, but the blow hit naught but air as the newest apprentice leaped backwards and into the air.

"Fire!" Xehanort shouted, aiming his Keyblade in front of himself and shooting a small fireball in the black-haired boy's direction.

"Freeze!" Eraqus exclaimed, aiming his own Keyblade and firing a Blizzard spell, launching a blast of ice that negated the opposing Fire spell, leaving only steam. "You've gotten better at using magic," Eraqus noted.

"You can thank Yen Sid for that," the silver-haired youth replied, before charging downwards to strike his fellow apprentice. However, when he was a mere few inches from attacking, Xehanort completely changed his direction in midair and circled behind Eraqus. The confusion this caused allowed the former islander to land a strike in Eraqus' backside, knocking him several feet forward and off his feet.

"Now there's a lesson for you, Eraqus. Always be ready for when your opponent throws you a curveball." Xehanort said triumphantly, a hint of snark in his voice.

Having gotten back on his feet, Eraqus twisted his upper body around and tossed his Keyblade like a boomerang, spinning around until it struck the opposing apprentice on the side of his head before returning to Eraqus' hands, stunning Xehanort momentarily and giving Eraqus time to cast another spell.

"Thunder!" Eraqus exclaimed, summoning a bolt of lightning above Xehanort's head in an attempt to strike him. However, much like before, Xehanort used his own speed to his advantage, deftly evading the attack so it only singed his coat. Before Eraqus could process what had happened, a blur of black and silver appeared before his eyes as Xehanort tried striking at the senior apprentice's shoulder, before seeing blocked yet again by the dark grey Keyblade.

In retaliation, the black-haired youth swung his arm to bring distance between himself and the novice, before returning to a clash of Keyblades, the two apprentices being even in strength. In another mere second, Xehanort retracted his weapon before swinging again, repeating the action alongside Eraqus a multitude of times in an attempt to break the other's guard.

"I might not be as strong as you, but strength is useless if you can't hit anything with it!" The former islander boasted, leaping back to create some distance before bolting ahead with such speed Eraqus could only perceive him as a blur, as he was suddenly struck from several directions while Xehanort was literally running circles around him. However, when Xehanort was readying what he thought would be the finishing strike, Eraqus had a sudden thought that he hoped would net him the victory.

"And with this, It's my win!" Xehanort yelled, before charging ahead. But, for the briefest of moments, he was curious as to why the opposing apprentice didn't raise his Keyblade in defense, though he shook the thought off soon enough as he reached closer.

"Reflect!" Eraqus shouted, creating a barrier between himself and Xehanort that managed to block the latter's strike and, before he could react, exploded with equal power to the previous attack, sending him backwards and straight into a nearby wall, nearly knocking him out. Although Xehanort attempted to get up and continue the fight, he found his legs refused to respond and his arms burned from the aftereffects of the clash, forcing the defeated apprentice to remain where he was.

A mere few seconds later, Yen Sid had arrived, and casted Cure to help the other boy up and bring him back to the courtyard, where Eraqus stood with a smirk on his face.

"Looks like I win this one, eh, Xehanort?" He asked, with a somewhat smug tone to the question.

"I guess you do Eraqus, I guess you do," Xehanort replied, admitting his own defeat. "I've definitely gotten more skilled, but it looks like I'm not besting my senior just yet."

"We may have all grown skilled in these years, but there is at least one thing we know for certain: We are still nowhere near the level of Keyblade Master, as you all can probably remember what occurred a mere five months ago," Yen Sid piped up, recalling the last time they had tested their skills against their Master.

"You mean the last time Master Inex more or less demolished us in a sparring session?" Xehanort asked rhetorically, as the three of them recalled the events that took place nearly half a year ago.

—

 _At around midday, within the Forecourt, Inex stood in the center with his hands behind his back, as Xehanort, Yen Sid and Eraqus circled him, all of their Keyblades drawn._

" _Now, apprentices, this shall be a rather simple training session. If any of you can hit me once, you win. If not, you lose. There is no penalty for failure, so do not be afraid to admit defeat. I will even be generous and not retaliate with my own Keyblade," Inex explained, keeping his hands clasped together as he beckoned them forward with a nod of his chin._

 _Xehanort was the one to make the first move, sprinting forward and attempting to strike his Master while his back was turned. Without even turning around, Inex had simply sidestepped the blow, before raising his arm in a chopping motion to strike at Xehanort's shoulder blades, knocking him to the ground._

" _Always the one to strike first, Xehanort." Inex muttered with a sigh, "You should know that impulsiveness can leave you at a disadvantage in a battle, if your opponent preferred to fight defensively, as you may or may not have realized from our exchange."_

 _Paying no heed to his master's words, Xehanort leapt back up and repeatedly lunged at Inex; but every time he attempted a strike, Inex evaded it with such speed that he looked like he was merely standing still. After several seconds, Inex retaliated, jabbing his elbow in Xehanort's stomach, causing the apprentice to fall to the ground, shocked and groaning in pain._

" _Well, that's one. Now, how would you two like to see how you fare?" The Master asked to his remaining two apprentices, who both had wide eyes at the scene before them._

 _Shaking the nervousness off, Eraqus was the next to attack, displaying his skill in magic by first attacking with Fire. However, the ball of flames seemed to simply disperse upon coming close to Inex's body, resulting in Eraqus being forced to physically strike his master, but with the first downward swing, Inex caught his Keyblade, effortlessly holding it despite his apprentice's efforts to remove it from his master's grip._

" _Eraqus, I thought you would have initiated the fight with your more complex abilities. Leading with nothing but your simplest moves can lend you a swift defeat if your opponent happens to take the offensive," Inex explained, before pulling the Keyblade out of his apprentice's hands and delivering a chop to the back of his neck, knocking Eraqus out cold._

 _As soon as Eraqus fell to the ground, Yen Sid took his opportunity and began casting several spells in succession._

" _Fire! Freeze! Thunder! Wind!" He yelled, firing off the corresponding spells in an attempt to catch Inex off-guard. In response, Inex proceeded to telekinetically redirect the Fire into the Blizzard and cancel them both, before evading the Aero and casting Reflega when he was about to be struck by the Thunder._

" _And you, Yen Sid, focus far too much on your magic capabilities. While they are impressive, especially for a trainee like yourself, your reliance on them could lead you into great danger if your enemy is able to counter, reflect, or render them ineffective. Now, Firaga!" Inex shouted, generating a massive orb of flames in the palms of his hands and throwing it towards his last apprentice, knocking him into the wall and singing his robe._

" _With that, I believe that I am the victor. Now, Xehanort, Eraqus, Yen Sid, you all possess incredible skill in the use of your Keyblades and magic, but you all have some sort of flaw that could severely hamper all three of you. Xehanort, you are too quick to the draw, Eraqus, you are too conservative with your abilities, and Yen Sid, you are too specialized in magic and lack particular prowess in physical combat. I hope that, by the time I name you all Keyblade Masters, you three will have addressed these deficiencies in your fighting styles," Inex explained as he walked back into the castle, leaving the three apprentices on the ground, defeated._

—

"Well, don't you worry you two. I plan to become a Keyblade Master if it's the last thing I do!" Xehanort exclaimed, pumping his fist in the air, eliciting chuckles from his fellow pupils.

Suddenly, the trio heard the deep ring of a large bell coming from the castle. That normally meant that Master Inex needed them for something important, but what could he possibly want to see them for today?

"Well, I believe the Master requests our presence," Eraqus said, as he, Xehanort and Yen Sid started their walk up the steps to see what Inex had needed them for.


End file.
